The human body has numerous biological valves that control fluid flow through body lumens and vessels. For example the circulatory system has various heart valves that allow the heart to act as a pump by controlling the flow of blood through the heart chambers, veins, and aorta. In addition, the venous system has numerous venous valves that help control the flow of blood back to the heart, particularly from the lower extremities.
These valves can become incompetent or damaged by disease, for example, phlebitis, injury, or the result of an inherited malformation. Heart valves are subject to disorders, such as mitral stenosis, mitral regurgitation, aortic stenosis, aortic regurgitation, mitral valve prolapse and tricuspid stenosis. These disorder are potentially life threatening. Similarly, incompetent or damaged venous valves usually leak, allowing the blood to improperly flow back down through veins away from the heart (regurgitation reflux or retrograde blood flow). Blood can then stagnate in sections of certain veins, and in particular, the veins in the lower extremities. This stagnation of blood raises blood pressure and dilates the veins and venous valves. The dilation of one vein may in turn disrupt the proper function of other venous valves in a cascading manner, leading to chronic venous insufficiency.
Numerous therapies have been advanced to treat symptoms and to correct incompetent valves. Less invasive procedures include compression, elevation and wound care. However, these treatments tend to be somewhat expensive and are not curative. Other procedures involve surgical intervention to repair, reconstruct or replace the incompetent or damaged valves, particularly heart valves.
Surgical procedures for incompetent or damaged venous valves include valvuloplasty, transplantation, and transposition of veins. However, these surgical procedures provide somewhat limited results. The leaflets of some venous valves are generally thin, and once the valve becomes incompetent or destroyed, any repair provides only marginal relief.
As an alternative to surgical intervention, drug therapy to correct valvular incompetence has been utilized. Currently, however, there are no effective drug therapies available.
Other means and methods for treating and/or correcting damaged or incompetent valves include utilizing xenograft valve transplantation (monocusp bovine pericardium), prosthetic/bioprosthetic heart valves and vascular grafts, and artificial venous valves. These means have all had somewhat limited results.
What is needed is an artificial endovascular valve for the replacement of incompetent biological human valves, particularly heart and venous valves. These valves may also find use in artificial hearts and artificial heart assist pumps used in conjunction with heart transplants.